Selective fluorescence sensing of polynitroaromatic explosives using triaminophenylbenzene scaffolds.

A supramolecular fluorophore, 1,3,5-tris(4'-aminophenyl)benzene (TAPB), selectively senses polynitroaromatic compounds (PNAC), viz. 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), picric acid (PA), m-dinitrobenzene (m-DNB) and p-dinitrobenzene (p-DNB) through donor-acceptor complexation. Steady-state and time resolved fluorescence measurements indicate predominantly static quenching of the TAPB fluorophore with TNT, DNT, m-DNB and p-DNB. In the case of PA, a new emissive band with a marginally longer lifetime emerges due to complex formation with TAPB. The selectivity of sensing action is rationalized through computation of HOMO and LUMO energies for both the fluorophore and the analytes using the M06-2X/6-311+G(d,p) level of theory. Practical utility of the fluorophore has also been demonstrated with TNT and DNT vapour.